A pointer for moving a cursor on a display for a computer may conventionally consist of a mouse provided with a ball, which is brought to rotate against a plane surface during the movement of the mouse. The relative movement of the mouse in different directions, and the corresponding rotating movements of the ball, cause a corresponding change of the coordinates of the cursor on the screen. A long movement on the screen in a certain direction may be achieved on a small surface by occasionally lifting the mouse during the movement and replacing it in a previous position.
One alternative to a conventional mouse consists of an arrangement comprising a control ball, which in a fixed position can be rotated around an arbitrary axis. The ball is resting in a special cradle, provided with sensors, which translates the movements of the ball into corresponding, relative changes of the coordinates of the cursor. One advantage with this alternative is that long movements in the same direction is easily achieved by a continuous rotation of the ball around the same axis.
In another case, the pointer may comprise a keypad, by means of which a change in the coordinates of the cursor is achieved by a finger being moved over the keypad in various directions, while the finger is lightly pressed against the keypad. A long movement in the same direction can take place in a similar way as with a mouse, by lifting the finger during the movement and replacing it in a previous position.
In order to achieve click functions in the above cases, two keys are normally used, one key for “left click” and “double click” and another key for “right click”. In the latter case, in which the pointer comprises a keypad, the “left click” and “double click” functions may alternatively be achieved by a tap with the finger on the keypad once or twice.
In the example mentioned above, it is normally assumed that the user is working at a table or a desk, onto which, at least, the pointer, keyboard and possibly also the screen are placed. A pointer, in particular, requires actually that an essentially plane surface with a certain area is available for the movements of the mouse. In other cases, the conditions may be different, for example when a table arrangement or the equivalent is missing. Hereby, a need exists for a different kind of pointer, which can be directly activated by the user without any need for an underlying surface. One example of this is described in Patent Abstracts of Japan 10301706A. This pointer comprises a small, short stick for movement of the cursor on the screen. The stick is mounted on a cylindrically shaped housing, which can be slipped on one of the forefingers. The pointer also comprises switches for the click functions corresponding to the left and right clicks on a mouse, and a radio transmitter for transferring relevant signals to a host computer. According to another example, described in Patent Abstracts of Japan 11015597A, a pointer with a fixed part and a movable, fingertip-handled ball is used. The fixed part comprises a holder for the ball and is provided with a click function. The fixed part is also provided with a string to be applied to a finger.
A disadvantage with the above described pointers is that the devices for adjusting the coordinates of the cursor on the screen, i.e. the short stick in the first case and the ball in the second case, have small dimensions, thereby making their handling more difficult compared to the previously described pointers. This is also the case for the devices controlling the click functions. A high accuracy in finger movements is required and more time may be needed in order to exactly adjust the coordinates of the cursor and activate a click function, especially for a person having a limited fine-motoric ability.
The use of a pointer for the control of the cursor of a computer screen or display is a risk factor for strain injuries. The use of a ordinary computer mouse for a stationary computer may cause pain, i.a. in the right of left arm and in the corresponding shoulder and wrist.
Thus, a need exists of an improved pointer for control of a cursor, both for large, stationary computer screens, portable computers (laptops), small palmtop displays and so called screenglasses, which reduces the risk for strain injuries, which does not require a plane surface or a special keypad on the computer, and which, at the same time, is easy to handle and has an efficient click function, and which can be easily handled by persons with a limited fine-motoric ability, as well.